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MS Office Forum / Word / Programming / September 2007Working with SUBs
Kinda new to writing subroutines within VBA. I didn't realize that all the module-level variables declared in the body of the procedure are not available to you in the SUB. I guess I have to pass any that are needed in the SUB, as arguments? Is there another technique? Hi Rick, One way is that you pass the specific variables among the subs. However there are various scoping rules for the variables in VBA (Word and Excel) Check out these links to learn more about it- http://www.ozgrid.com/VBA/variable-scope-lifetime.htm http://support.microsoft.com/kb/183369 http://www.ozgrid.com/VBA/variables.htm  SignaturePranav Vaidya VBA Developer PN, MH-India If you think my answer is useful, please rate this post as an ANSWER!! > Kinda new to writing subroutines within VBA. I didn't realize that all > the module-level variables declared in the body of the procedure are not > available to you in the SUB. I guess I have to pass any that are needed > in the SUB, as arguments? Is there another technique? Here's another link: http://www.word.mvps.org/FAQs/MacrosVBA/ProcArguments.htm One point that I didn't see mentioned in any of these articles: Although declaring a variable at module or global scope seems to be an easy way to get information to all the procedures that use it, that is usually not a good choice. The problem is that such variables can be changed by any procedure that can see them, and that's a breeding ground for bugs. It's much better from the standpoint of maintainability to pass arguments, using ByRef and ByVal modifiers when necessary, and to use functions (which return a value) when that makes sense. SignatureRegards, Jay Freedman Microsoft Word MVP FAQ: http://word.mvps.org Email cannot be acknowledged; please post all follow-ups to the newsgroup so all may benefit. > Hi Rick, > [quoted text clipped - 11 lines] >> that are needed in the SUB, as arguments? Is there another >> technique? And when you say 'pass' the variables among the subs, you mean as arguments, right? > Hi Rick, > [quoted text clipped - 5 lines] > http://support.microsoft.com/kb/183369 > http://www.ozgrid.com/VBA/variables.htm > Kinda new to writing subroutines within VBA. I didn't realize that all > the module-level variables declared in the body of the procedure are not > available to you in the SUB. Before you start confusing yourself and everyone else here, let's get some terminology straight. Module-level variables are declared *before* the first Sub or Function in the module. They are declared using the keyword Private rather than Dim. A module level variable can be used by any routine within the same module. Global variables are also declared before the first Sub or Function of a module, but using the Public keyword. A global variable can be used by any routine in any module of the project. Procedure-level variables are declared after the Sub or Function statement at the start of a procedure, and are only available within that procedure. > I guess I have to pass any that are needed > in the SUB, as arguments? That is usually the best way. > Is there another technique? Yes, you can use global or module level variables, but I would recommend being very sparing with their use. If you declare a variable locally and pass it as a parameter to another routine, you know that there is only one point at which the two routines interact. With a module-level or global variable, any routine can affect the operation of any other simply by changing the value of a common variable, and as there is no limitation as to how and where this can happen, bug-hunting can take on needle-in-a-haystack dimensions You might be interested in this article which describes some additional techniques for writing maintainable code. The art of defensive programming http://www.word.mvps.org/FAQs/MacrosVBA/MaintainableCode.htm SignatureRegards Jonathan West - Word MVP www.intelligentdocuments.co.uk Please reply to the newsgroup |
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